Some known electrophotographic image forming apparatuses, for example, form a developer image onto a photosensitive layer of a photosensitive member. The photosensitive member contacts a member, and slides relative to the member during rotation. Sliding of the photosensitive member relative to the member causes friction therebetween, thereby causing charge accumulation inside the photosensitive layer of the photosensitive drum. Such charge accumulation may change a relationship between a charge current, which passes through a charger for charging the photosensitive member, and a surface potential of the photosensitive member, thereby failing to control the surface potential of the photosensitive drum to have a desired surface potential.
In order to solve such a problem, some known technique has been used. In the known technique, for example, an accumulated charge quantity in the photosensitive layer is predicted. Based on the prediction, the larger the accumulated charge quantity is present, the greater the absolute value is specified for a charge voltage or the charge current (e.g., the magnitude of the charge voltage or charge current is increased over the magnitude of an initial charge voltage or charge current). More specifically, in the known technique, the accumulated charge quantity is predicted based on, for example, a transfer current, a rotating speed of the photosensitive member, and/or temperature.